Concurrent headache and fever signal systemic or neurologic processes. The pattern and associated features guide diagnosis and urgency.
Common Infectious Causes
- Viral URI/Influenza/COVID-19: Headache, fever, myalgia, respiratory symptoms.
- Sinusitis: Frontal/maxillary pain, purulent discharge, fever, worse bending forward.
- Meningitis: Headache, fever, nuchal rigidity, photophobia, altered mental status – emergency.
- Encephalitis: Fever, headache, confusion, seizures, focal deficits.
- Sepsis: Fever, tachycardia, hypotension, altered mentation.
Non-Infectious Causes
- Medication-Induced: Drug fever + headache (antibiotics, allopurinol, biologics).
- Autoimmune/Inflammatory: SLE, vasculitis (GCA – temporal headache, jaw claudication, vision threat), sarcoidosis.
- Malignancy: Lymphoma, leukemia, metastatic disease.
- Thrombosis: CVST (headache, papilledema, seizures), PE (pleuritic pain, dyspnea).
- Heat-Related Illness: Heat exhaustion/stroke.
Primary Headache with Fever-Like Features
- Migraine: Can have “feverish” feeling, chills; no true fever.
- Cluster: Autonomic features (lacrimation, nasal congestion).
Red Flags (Emergent Evaluation)
- Thunderclap headache (maximal intensity <1 min)
- Fever + new neurologic deficit
- Immunocompromised + fever
- Post-traumatic (recent head injury)
- Papilledema, focal signs, seizure
- Age >50 new-onset headache (GCA)
- Pregnancy/postpartum
Initial Workup
- Vitals, neuro exam, fundoscopy
- CBC, BMP, LFTs, CRP/ESR, blood cultures (if septic)
- CT head (if focal signs, thunderclap, immunocompromised)
- LP (if meningitis/SAH suspected; CT first if indicated)
- COVID/flu/RSV panel
